The present invention relates to an integrated circuit for power conversion, and more specifically to an integrated circuit for power conversion that uses III-nitride power semiconductor switches in the power conversion stage as well as the driver stage thereof.
III-nitride heterojunction power semiconductor switches are known. For example, Khan et al., U.S. Pat. No. 5,192,987, discloses one type of depletion mode III-nitride HEMT, while Beach, U.S. Pat. Pub. 2006/0060871 discloses examples of several types of enhancement mode III-nitride HEMTS.
III-nitride switches are particularly desirable for power applications because of the relatively higher band gap of the III-nitride material, the relatively low resistivity of the switch during conduction, and high frequency switching abilities.
It is an object of the present invention to provide an integrated circuit for power conversion in which the switches in the power stage as well as the switches in the driver stage are III-nitride switches.
An integrated circuit according to the present invention includes a power conversion bridge between a bus voltage and ground, and including a switched node for supplying current to an output circuit, and a driver stage that includes a first section and a second section, the first section being between a negative supply voltage and ground, and the second section being between the switched node and a derived voltage below the switched node derived from the negative supply voltage.
In one embodiment, the power conversion bridge includes a high side III-nitride switch and a low side III-nitride switch series connected with the high side III-nitride switch to form a half-bridge. In the preferred embodiment, the first and the second III-nitride switches are depletion mode devices. Moreover, in the preferred embodiment, the first section and the second section each includes a driver bridge comprised of two series connected III-nitride switches in a half-bridge arrangement having an output thereof coupled to a respective gate of one of the high side III-nitride switch and the III-nitride low side switch. In one embodiment, the series connected III-nitride switches in each the first section and the second section are enhancement mode devices. In another embodiment, the series connected III-nitride switches in each the first section and the second section are depletion mode devices.
Disclosed herein is also a novel level shifting scheme for level shifting a PWM signal before it is supplied to the drive stage.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.